<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let obj ={}
    //  Object.defineProperty(obj,'name',{
    //      value:'yjj',
    //      enumerable:true,
    //      writable:true,
    //      configurable:true,
    //  })  
     Object.defineProperty(obj,'age',{
         get(){
            return '111' 
         },
         set(val){
            console.log(val)//222
         }
     })
        obj.age= 222
      console.log(obj.age) //111
      console.log(obj)
    </script>
</body>
</html>